Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutathione: dehydroascorbate reductase activity was studied in rat liver, heart, spleen, lungs as well as in Zajdela hepatoma. Correlation between the activities of glutathione reductase and glutathione: dehydroascorbate reductase was observed in all the tissues studied. Glutathione: dehydroascorbate reductase activity was higher in Zajdela hepatoma as compared with the rat liver. The role of glutathione: dehydroascorbate reductase in regulation of antioxidative activity and of cell division is discussed.
 ...
PMID:[Glutathione: dehydroascorbate-oxidoreductase activity in rat tissues]. 47 87

The activity of NADPH- and NADH-dependent erythrocyte glutathione reductase was determined in rats with Morris 5123 hepatoma at different stages of tumor development (10, 20, 30 and 40 days after transplantation). During the early stage of tumor growth the activity of glutathione reductase with either of these coenzymes was increased. In the late stage of the disease the activity of NADPH-dependent glutathione reductase fell below control values. The obtained results are discussed in the light of previous observations on the effects of this neoplasm on the metabolism of erythrocytes.
 ...
PMID:[Glutathione reductase activity in erythrocytes of rats with transplantable Morris 5123 hepatoma]. 73 12

Treatment of isolated mitochondria from rat hepatoma tumor cells (AS-30D) with the oxidant, t-butyl hydroperoxide (tBuOOH, 1 or 5 mumol/ml) resulted in the oxidation of glutathione (GSH to GSSG) and the formation of protein-glutathione mixed disulfides (ProSSG). The GSSG was retained inside of the hepatoma mitochondria. In the presence of ADP+succinate (5 or 10 mM), or ketoglutarate (10 mM) or malate (5 mM), the GSSG was reduced to GSH, but the amount of ProSSG stayed constant. With saline or ADP+glutamate (10 mM)/malate (0.1 mm) no reduction of GSSG to GSH occurred. The presence of antimycin (5 micrograms/ml) with ADP+succinate inhibited reduction. At a concentration of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, 0.5 mM) which inhibited a major portion of the glutathione reductase activity, the reduction of GSSG to replenish GSH was also inhibited. NADPH may play a critical role as well, for the addition of 2.4 mM NADPH to permeabilized hepatoma mitochondria fostered the reduction of GSSG after tBuOOH treatment. Therefore, hepatoma mitochondria possess a glutathione reductase-dependent system to reduce GSSG to GSH. The reaction only occurs with actively respiring mitochondria.
 ...
PMID:Glutathione disulfide reduction in tumor mitochondria after t-butyl hydroperoxide treatment. 139 20

We have compared some mechanisms involved in the defense against doxorubicin-induced free radical damage in rat hepatoma and glioblastoma cell lines and their doxorubicin-resistant variants presenting an overexpression of the multidrug resistance gene. Immediate in vivo production of malondialdehyde was minor and was not different in sensitive and resistant cells. Alpha-tocopherol was undetectable in all cell lines. Glutathione levels were not different in sensitive and resistant cells and these levels did not vary upon doxorubicin treatment. Resistant cells exhibited either a 50% decrease (hepatoma) or a 25% increase (glioblastoma) of glutathione-S-transferase activity. Glutathione reductase presented no important change upon acquisition of resistance. In contrast, selenium-dependent glutathione peroxidase activity was consistently 2-6-fold increased in the resistant cells, which suggests a magnification of protection mechanisms against hydroxyle radical formation from H2O2 in resistant cells. Depletion of glutathione levels by buthionine sulfoximine sensitized hepatoma resistant cells to doxorubicin, but had no effect on doxorubicin cytotoxicity to glioblastoma cells.
 ...
PMID:Development of mechanisms of protection against oxidative stress in doxorubicin-resistant rat tumoral cells in culture. 196 16

The cytotoxic properties of quinone drugs such as menadione and adriamycin are thought to be mediated through one-electron reduction to semiquinone free radicals. Redox cycling of the semiquinones results in the generation of reactive oxygen species and in oxidative damage. In this study the toxicity of mitozantrone, a novel quinone anticancer drug, was compared with that of menadione in human Hep G2 hepatoma cells. Mitozantrone toxicity in these cells was not mediated by the one-electron reduction pathway. In support of this, inhibition of the enzymes glutathione reductase and catalase, responsible for protecting the cells from oxidative damage, did not affect the response of the Hep G2 cells to mitozantrone, whereas it exacerbated menadione toxicity. In addition, the toxicity of menadione was preceded by depletion of reduced glutathione which was probably due to oxidation of the glutathione. Mitozantrone did not cause glutathione depletion prior to cell death. DT-diaphorase activity and intracellular glutathione were found to protect the cells from the toxicity of both quinones. Inhibition of epoxide hydrolase potentiated mitozantrone toxicity but did not affect that of menadione. Our experiments indicate that mitozantrone toxicity may involve activation to an epoxide intermediate. Both quinone drugs inhibited cytochrome P-450-dependent mixed-function oxidase activity, although menadione was more potent in this respect.
 ...
PMID:The toxicity of menadione and mitozantrone in human liver-derived Hep G2 hepatoma cells. 253 22

The existence of membrane-bound forms of glutathione reductase in rat liver and transplantable hepatoma G-27 was demonstrated, using differential centrifugation techniques. The activity of the sedimentable form of the liver enzyme was detected only in the presence of detergents. Conditions for the manifestation of the latent glutathione reductase activity in whole liver homogenates and in the 105000 g pellet were determined. Solubilization of the latent form of the enzyme in the presence of sodium deoxycholate increases 2-fold the glutathione reductase activity in liver homogenates (but not in hepatoma). Simultaneous determination of the disulfidereductase, nonspecific NADPH-oxidase and gamma-glutamyltransferase (membrane-bound enzyme of glutathione metabolism) activities was performed.
 ...
PMID:[Latent form of glutathione reductase in the rat liver]. 287 72

The importance of some glutathione metabolic pathways was examined in two highly dedifferentiated hepatomas, Yoshida AH-130 and Morris 3924 A hepatomas, and in normal liver in relation to their role against oxidative stress. The cytosol prepared from Yoshida hepatoma cells decreased the peroxidation rate in normal liver microsomes and mitochondria, but this antioxidant property was not displayed by Morris hepatoma. Glutathione peroxidase and glutathione-S-transferases activities were extremely low in both hepatomas; glutathione reductase activity values were about half the normal liver values. The large decrease in glutathione peroxidase and glutathione-S-transferases suggests that in these two tumors only small amounts of GSH can be used in reduction or conjugation reactions, such as the reduction of hydrogen peroxide and lipid hydroperoxides or the conjugation of GSH with the end products of lipoperoxidation, aldehydes or ketones. The hypothesis of a more efficient GSSG reduction in hepatomas, due to the low glutathione peroxidase/glutathione reductase activity ratio, is also discussed. The described changes in glutathione related enzymes do not seem to have any correlation with the protective effect against the lipoperoxidative processes displayed by some tumors since these enzymatic activities were similar in both hepatomas whereas only Yoshida hepatoma showed antioxidant properties.
 ...
PMID:Analysis of glutathione-dependent enzyme activities in two different rat hepatomas and in normal liver in relation to their role in resistance to oxidative stress. 323 5

Studies were carried out on microsomes isolated from the highly differentiated (slow-growing) Morris hepatoma 9618A, on microsomes and plasma membranes from the poorly differentiated (fast-growing) Morris hepatoma 3924A, and rat liver used as control. The lipid composition (phospholipid and cholesterol content, degree of fatty acid unsaturation) and peroxidation of such membranes has been correlated with the order and fluidity of the membrane bilayer. The results indicate that substrate availability is the rate-limiting step in microsomal and plasma membrane lipid peroxidation of hepatoma 3924A. From diphenylhexatriene fluorescence depolarization measurements it appears that the changes in lipid composition cause an increase in the order of the lipid bilayer on going from the control to hepatoma 9618A and 3924A microsomes, while fluidity is virtually unchanged. Conversely, for similar chemical changes, in plasma membranes from hepatoma 3924A the order is nearly the same and there is a decrease in fluidity. The changes in the above parameters of tumor membranes might be partly related to the loss of protective enzymes against oxygen radicals. This is supported by the observation that inhibition of liver superoxide dismutase and glutathione reductase, by treatment of rats with diethyldithiocarbamate and chloroethyl nitrosourea, respectively, renders the microsomal membranes more resistant to lipid peroxidation in vitro.
 ...
PMID:Lipid composition, physical state, and lipid peroxidation of tumor membranes. 609 10

Erythrocyte transketolase (ETK), glutathione reductase (EGR) and glutamate pyruvate transaminase (EGPT) enzyme activities and coenzyme effects (in vitro coenzyme stimulation) were studied in 30 random, 10 primary hepatoma, and 3 pellagrins natives from Mozambique. Twenty-nine subjects of the random group exhibited ETK coenzyme effects below 20%. Urinary thiamine levels in this group were in normal or high ranges. The primary hepatoma group had 4 with ETK coenzyme effects above 30%, and 3 of the 4 had low level urinary thiamine excretions. Of the three pellagra patients in the study, none showed biochemical vitamin B1 deficiency. All primary hepatoma and 23 random natives had EGR coenzyme effects above 30%, but the daily urinary riboflavin excretions correlated with the coenzyme effect in only the random group. EGPT activities were spread over a wide range. The random group with high EGPT activity showed a correlation with low coenzyme effect, while the primary hepatoma group did not exhibit this correlation. After 4-day single-vitamin treatment, vitamin B1 increased total ETK and vitamin B2 increased total EGR (after in vitro coenzyme saturation). Vitamin B6 did not increase total EGPT. Vitamin B2 was less effective on total EGR in primary hepatoma than in random subjects.
 ...
PMID:Effects of vitamins B1, B2, B6 and C on erythrocyte enzymes in South African Bantu. 629 84

We report changes in free radical-metabolizing enzymes and the increased generation of lipid peroxides associated with extreme metal accumulation in the liver of the Long-Evans with cinnamon-like coat color (LEC) rat, a new mutant strain displaying hereditary hepatitis and subsequent hepatocellular carcinoma. The activity of free radical-metabolizing enzymes and lipid peroxides, and the concentration of metal in the liver were determined sequentially after birth. Mn-superoxide dismutase activity significantly increased immediately after the onset of hepatitis in LEC rats, whereas no remarkable change was observed in control rats. Cu, Zn-superoxide dismutase activity in LEC rats was similar to that in control rats. Glutathione reductase activity increased, while glutathione peroxidase activity was lower in LEC rats than in control rats throughout the observation periods. Lipid peroxides, estimated by thiobarbituric acid reaction, also increased 4- to 5-fold immediately after the onset of hepatitis in LEC rats. Copper concentration was 30- to 50-fold higher in the liver of LEC rats than in control rats, and the iron content also increased significantly before and after the onset of hepatitis. These findings suggested that an oxidant injury generated by toxic metals could be one of the factors responsible for hepatocellular damage in this unique hereditary hepatitis.
 ...
PMID:Changes in free radical-metabolizing enzymes and lipid peroxides in the liver of Long-Evans with cinnamon-like coat color rats. 857 34


1 2 3 4 5 6 Next >>